In some assignments of radio spectrum, channels from adjacent blocks may be allocated to the same operator but for different operations. The operation may require transmissions in one block and reception in the adjacent block. Various operators may have channels assigned at the common edge between blocks, which are called edge channels, such that all the available channels in both blocks are allocated. However, a mobile unit that is capable of universal operation such that the mobile unit is capable of flexibly receiving and transmitting across all channels in each block, including the edge channels, does not currently exist.
In order to transmit and receive in adjacent blocks of the radio spectrum, a filter is used to separate a transmit signal in one block from a receive signal in the adjacent block. Conventional systems that use adjacent blocks of spectrum separate the signals using filters with a transition band between the channels in operation. In the case of adjacent or very closely adjacent channel assignments, the transition band of the filter overlaps one or more of the desired channels and hence renders that channel unusable for the system. These unusable channels are commonly referred to as transition band guard-channels. This results in a loss of spectrum availability and loss of universality of access to the services by generic mobile units. So far, this problem has thwarted the commercial use of such adjacent spectrum assignments as generic mobile user equipment (UE) cannot be produced. As a result, radio spectrum owners are unable to fully utilize the radio spectrum which they have paid to purchase. For example, in the IMT-2000 mobile bands in Europe and many other areas of the world, the entire auxiliary band from 1900 MHz to 1920 MHz is currently unutilized because of this problem. There is ongoing discussion in the 3rd Generation Partnership Project (3GPP) on topics of using unpaired channels in the auxiliary band, particularly for Broadcast TV services; however the problem described above has thus far prevented such a use.
Wireless access networks use control signalling to manage their operation. In some systems (e.g. 1xEV-DO) the various physical control channels are designed to carry fixed sized control signalling. This is inefficient for handling variable sized control signalling for broadband access systems. To avoid this problem control signalling is transmitted using messages on a broadcast channel on some networks (e.g. IEEE 802.16 based networks). That is to say, a dedicated control channel concept is not used. The problem is that such an approach introduces additional overhead, such as message type and CID to identify recipient and so on.